Summary: In previous studies, we successfully developed a two step affinity chromatography procedure to purify RAT ovarian LH/hCG receptors to homogeneity and partially characterized the molecular composition of PURE rate LH/hCG receptors. It is our intention in the proposed research to purify PIC luteal LH/hCG receptor to homogeneity using the methodology we have developed in the rat system. Furthermore, we intend to (1) analyze the physico-chemical and binding properties of the purified receptor; (2) demonstrate the isolation of functional LH/hCG receptors by reconstitution of partially purified and purified receptors into hepatoma cell membranes and intact hepatoma cells; (3) to raise monospecific antibodies (Ab) to LH/hCG receptors in rabbits. The Ab will be characterized for their biological and immunochemical properties. The molecular basis of receptor regulation by hormones will be analysed by specific immunoprecipitation and immunocytochemical methodology. Receptor Ab will provide use with a superb analytical tool to study the molecular biology of receptor regulation and for electron microscopic immunocytochemical studies on receptor synthesis, processing and turnover. These receptor antibodies will not only be of great value in furthe relucidation of the role of LH in ovarian functon but may also have significant practival application in contraception and in understanding infertility of ovarian origin.